Method and apparatus for inerting head space of a capped container

ABSTRACT

A process to reduce oxygen in the head space of containers includes introducing an inert gas into the container head space. This may be accomplished during a capping process. Multiple conduits may be used to introduce the inert gas. The one or more conduits may be angularly offset from either or both of a plane defined by the opening of the containers and a direction of movement of the containers at the time the inert gas is introduced. In certain embodiments, the openings of the one or more inert gas conduits may be remote from spaces defined by projections of the container openings.

BACKGROUND OF THE INVENTION

It has long been recognized that removing gaseous oxygen from sealed containers containing potable liquids can extend their shelf lives by reducing the rate of spoiling from microbial attack. Vacuum packaging and the use of bags have been used to eliminate gas altogether from packaging, but inerting, or the filling of the unfilled container space with an inert gas, is also widely used.

In a popular method of inerting, a small dose of liquid nitrogen is injected into a filled container just prior to capping. The nitrogen vaporizes, which displaces oxygen from the container's head space during capping. Some liquid nitrogen remains in the container after capping and vaporizes in the sealed container, which pressurizes the container. However, this method is not useful for non-pressurized containers such as milk and juice bottles. The snap-on caps for these containers are not designed to withstand the pressures developed by the vaporized nitrogen, and the increased pressure created by the vaporized nitrogen breaks the seal between the cap and bottle, allowing air to be sucked back into the container during handling and shipping, renewing microbial attack. As a result, shelf life of non-pressurized capped containers is not significantly extended using this method.

Methods have been developed for inerting the head space in non-pressurized containers such as the classic gable-top paper container. U.S. Pat. No. 6,634,157 issued to Anderson et al. on Oct. 21, 2003 discloses an apparatus and method for filling these containers. It makes used of a special nozzle inserted into the container after filling with product and prior to sealing the container. The inerting step must be carried out as a separate step between filling and sealing the container, and therefore adds more time to the overall packaging cycle, which reduces throughput. Also, the apparatus for positioning, operating and removing the nozzle is complex and relatively expensive.

SUMMARY OF THE INVENTION

In general, an invention having the desired features and advantages is achieved by injecting an inert gas such as nitrogen simultaneously into the head space of a filled container and the cap used to seal the container during the capping procedure.

In one example embodiment, a method is provided for extending shelf life of a potable liquid in a container sealed by a cap enclosing an opening of the container. The container and cap cooperate to define a head space above the potable liquid. One step of the method is changing the relationship between the cap and opening from a first position to a second position, wherein a distance between the cap and opening is smaller at the first position than at the second position. Another step is introducing an inert gas toward the opening when the cap and opening are at the second position. Another step is sealing the cap on the container with the inert gas enclosed in the head space. The inert gas is delivered from an apparatus having an opening remote from a space defined by a projection of the opening of the container.

In another example embodiment, an apparatus is provided for introducing an inert gas into a head space of a container. The container and cap cooperate to define the head space above a potable liquid in the container. The apparatus includes an inert gas source and at least one conduit coupled to the inert gas source. The at least one conduit has an exit opening for the inert gas to exit the at least one conduit. The apparatus further includes a capping device for disposing a cap onto the container to seal the container. The apparatus is operable to introduce an inert gas into the head space as the relationship between the cap and opening are changed from a first position to a second position. A distance between the cap and opening is smaller at the first position than at the second position. The exit opening of the at least one conduit is remote from a space defined by a projection of the opening of the container.

The present invention has advantages over other methods and apparatus for inerting. Less equipment and space is needed than for apparatus using an inert gas filled environment. The apparatus for carrying out the method of the invention can easily be adapted to existing capping equipment. The inerting process provides improved reduction of oxygen within the container. The inerting process can be carried out between filling and capping the container without adding any time to the overall process. Additional features and advantages of the invention will become apparent in the following detailed description and in the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a front schematic elevation of an inerting apparatus according to an example embodiment;

FIG. 2 is a right side elevation of the apparatus shown in FIG. 1;

FIG. 3 is a front elevation for an alternate apparatus embodiment;

FIG. 4 is a front elevation for another apparatus embodiment;

FIG. 5 is an elevation of a container and portion of an inerting apparatus according to an example embodiment;

FIG. 6 is a plan view of a container opening and inerting apparatus according to an example embodiment;

FIG. 7 is a plan view of a container opening and inerting apparatus according to an example embodiment;

FIG. 8 is an elevation of a container and inerting apparatus according to an example embodiment;

FIG. 9 is an elevation of a container and inerting apparatus according to an example embodiment; and

FIG. 10 is a plan view of multiple containers and inerting apparatus according to an example embodiment in a rapping and inerting process.

DETAILED DESCRIPTION OF THE INVENTION

A need remains for an effective method and apparatus for inerting a beverage container. Such a method preferably should work with established capping apparatuses and require a minimum of space for the inerting apparatus. In addition, a method and apparatus that can perform the inerting without adding additional time to the overall filling/sealing procedure would be considered advantageous.

FIGS. 1 and 2 show a typical apparatus for capping one-gallon plastic milk bottles. The apparatus 11 is shown in schematic with nonessential equipment removed for visibility. Throughout the figures, which are not drawn to scale, equivalent elements are given identical reference numbers. While snap-on caps are shown, it is believed screw-on caps can also make use of the method of the invention for low pressure service, i.e. service in which the pressure in the sealed head space can range from slightly below to slightly above atmospheric pressure when capped, but not at high enough pressure to require a container with features designed to handle elevated pressure (e.g. bottles for carbonated beverages). Therefore, the term ‘cap having a top member and a skirt depending from the top member and defining a skirt volume’ is intended to include both the snap-on caps shown and screw-on caps and caps of other suitable configurations.

A chute 13 is used to transport caps 15 to the bottles 17. Each cap 15 has a top member 19 and a skirt 21 depending from the top member 19 and defining a partially enclosed skirt volume 23 with the top member 19. At the end of the chute 13, a pivotable arm (not shown) holds the next cap 15 to be used in the proper position for being put onto a bottle 17. As the bottle 17 moves along the conveyer track 25 past the cap 15, the skirt 21 engages the bottle 17. The moving bottle biases the cap 15 so that it is released by the pivotable arm and passes under a plate 29 that biases the cap downward, sealing it onto the bottle 17.

The apparatus 11 of the invention comprises a pair of injectors 31, 33 made from nominal half-inch copper tubing mounted on a header block 35 which in turn is attached by an adjustable linkage 37 to the chute 13. Flexible tubing 39 connects the header block 35 to a supply of pressurized nitrogen, preferably through a control loop having a control valve and flow controller (not shown), although other schemes can be used such as manually operated throttling valve and a pressure gauge located between the valve and the header block 35. An alternative embodiment is envisioned but not shown, wherein the header block 35 is absent and the injectors 31 and 33 are individually supplied by flexible tubing or other suitable conduit to the pressurized inert gas supply.

Because the injectors must be located close to the chute 13, the injectors 31 and 33 are separated by a gap 41 to allow tags 43 extending from the caps 15 to pass between the injectors unobstructed. While simple copper tubing is shown, other types of injectors known in the art can also be used, including other cross sectional types such as dispersion fans. Jets and devices that produce a narrow gas stream are not prohibited but are not preferred since a narrow, high velocity gas stream is more likely to produce splashing or otherwise disturb the surface of the container contents. Regardless of the injector shape, one feature of this illustrated example is the proper orientation of the injectors 31, 33 so that the inert gas stream is directed at or just below the point where the cap skirt 21 initially engages the bottle, in order to ensure that both the bottle head space and the cap skirt volume are properly flushed by the inert gas. The adjustable linkage 37 allows the user to experiment with orientation for best results with various equipment models, when the apparatus 11 is retrofit on existing capping equipment. However, the adjustable linkage can be replaced with a fixed mounting bracket or other unadjustable hardware for a particular piece or model of equipment or when manufactured as an integral part of the capping equipment.

The flow of nitrogen is set from about fifty to about two hundred standard cubic feet an hour (SCFH) to ensure the desired reduction of the oxygen level in the head space of a one-gallon milk container. The injectors operate continuously, so that there is some waste of the inert gas in the time interval between containers. The injectors are angled at about fifteen to forty degrees from horizontal, and preferably from about twenty to twenty-five degrees from vertical, and oriented so that a significant part of the flow stream flushes the skirt volume 23. This is necessary because trials have shown that the gas trapped in the skirt volume 23 tends to displace gas from the head space during capping rather than being pushed out into the surrounding environment, so that the gas composition in the cap has a significant impact on the final gas composition in the sealed head space.

FIG. 3 shows an apparatus for use with another embodiment of the invention. This embodiment differs from the preferred embodiment in that the inert gas is injected separately into the head space and the skirt volume by two independent injectors 45 and 47. While this apparatus also works well, it is more sensitive to proper construction and orientation for optimal performance. Therefore, this embodiment is better suited to a fixed installation as shown, rather then being adjustable, although adjustability can still be used. FIG. 4 extends the use of multiple injectors even farther. In this embodiment, the inert gas is injected into the caps at more than one point along the delivery chute. The flow rates of the various injection streams can be set equal to each other, or varied as desired. Also, in the embodiments of FIGS. 3 and 4 it is possible, although not shown, to use different inert gases for the different injectors. For example, argon may be preferred for use in flushing the head space, as argon is significantly denser than air and will form a fairly stable and distinct layer within the head space, so that filling the head space will effectively prevent oxygen in the air from settling back into the head space. While carbon dioxide will also work well from a technical standpoint, it is not preferred as it tends to affect the taste of the container contents. Argon's density and tendency to stratify, which help when inerting the head space, work against it in attempting to effectively inert the skirt volume, which is inverted. Here, nitrogen may be more desirable, as it more nearly matches the density of air, and does not stratify, so that it will tend to remain in the skirt volume longer.

The flow of inert gas may be selected so that the oxygen level in the sealed container is less than about fourteen percent by volume, and preferably less than about twelve percent by volume. By contrast, the prior art does not mention any allowable upper limit for oxygen content, and generally implies that proper inerting requires removal of essentially all oxygen from the head space. The inventor has discovered that practical extension of shelf life occurs even when oxygen levels in the head space are as high as about fourteen percent, with shelf life increasing with decreasing oxygen level. As the oxygen level is reduced below six percent by volume, there is a diminishing return to how much shelf life is extended with reduced oxygen level. The discovery that, in certain circumstances, the head space need not be flushed completely free of oxygen makes these example embodiments practical. For example, in certain situations, it is not necessary to insert an inert gas injector into the head space in order to ensure complete flushing of the head space, so the apparatus can be achieved without interfering with the conventional operation of the capping equipment, so there is no throughput penalty. Since complete removal of oxygen is not required, there is no need to create an oxygen-free environment around the container during capping, which eliminates the need for expensive, complicated and bulky apparatus for creating an artificial contained atmosphere around the bottles.

The invention has several advantages over the prior art. The method can be carried out simultaneously and independently of the conventional capping process, so throughput is essentially unchanged. The apparatus is simple and inexpensive to install, and requires relatively little space, especially in comparison to methods and apparatus that create an enclosed low-oxygen atmosphere surrounding the containers during capping. Existing capping equipment can be easily retrofitted to practice the method of the invention.

In still another embodiment, the inert gas may be introduced into the head space via one or more conduits as illustrated in FIGS. 5-10. These conduits may be similar to those previously described herein. However, in certain cases, the conduits may comprise tubes having relatively uniform cross-sectional areas along their respective lengths. The conduits may comprise tubes constructed, for example, from stainless steel.

As illustrated in FIG. 5, for example, first and second conduits 501 and 502 are provided to introduce inert gas into the head space defined by a container 17 and a cap 15, the head space being the space located above the potable liquid. First conduit 501 has an exit opening 503 and second conduit 502 has an exit opening 504. The conduits direct the inert gas from a source (not expressly shown) to the respective exit openings and generally in the direction of the opening of the container 17. In certain embodiments, this is done as the container is being brought into close proximity and/or contact with the cap 15 exiting the cap chute 13. However, the inert gas may be directed toward the container opening at other points during the processing. It should be noted that although two conduits are shown, various embodiments may incorporate only one conduit or more than two conduits.

Each of the conduits 501 and 502 is shown with a bend. However, a bend is not required and the conduits may have any suitable configuration. The configuration of the conduits may depend, for example, on other processing equipment. Also, one conduit may be configured differently than the other conduit.

As illustrated in FIG. 6, for example, the exit opening 603 of a conduit 601 is preferably remote from a space defined by a projection of container opening 607. Thus, the end opening is laterally spaced a distance A from the edge of the container opening 607. FIG. 6 is a top view of the container opening 607 in an example process. Thus, in the example process, the exit opening 603 does not physically penetrate the space defined by the upward projection of the container opening 607. This should prevent any condensation that may occur within or on the conduit 601 from dripping down into the container opening 607. Consequently, contamination from condensation drips may be avoided. The distance A may be determined based at least in part on one or more criteria including, without limitation, the desired flow pressure and/or velocity of inert gas exiting the conduit, the desired flow pressure and/or velocity of inert gas as it reaches the container opening, and the size and/or shape of the opening.

FIG. 7 illustrates an example configuration of two conduits with respect to their angular offsets from the direction of movement of a container during processing. Dashed line 708 represents a direction of movement of the container at the time the inert gas is introduced into the head space. This may occur, for example as the container moves close to the cap chute. First and second conduits 701 and 702 have first and second exit openings 703 and 704 respectively. Dashed lines 705 and 706 represent the respective lateral axes of first and second conduits 701, 702. The lateral axes are determine with respect to a plane defined by a projection of line 708 perpendicular to the plane defined by the container opening 707. First conduit lateral axis 705 is angularly offset from axis 708 by B degrees. Similarly, second conduit lateral axis 706 is offset from axis 708 by B degrees. Although the angular offsets are shown as being the same, the respective offsets may be different. Also, as shown in FIG. 10 for example, a conduit might have zero offset from the direction of movement and still not penetrate the container opening projection. Returning to FIG. 7, the lateral angular offset B is preferably in the range of from 30 to 50 degrees. More preferably, the range is from 40 to 45 degrees. Although the angular offset may be determined in this manner, the offset may also be determined with respect to the lateral flow direction of the inert gas as compared with the direction of movement of the container. Generally, it is expected that the inert gas exits the conduits in the same lateral direction as their respective lateral axes. However, in certain configurations, this might not be the case. For instance, a deflector (not shown) might be desired to change the flow direction of the inert gas after exiting from the conduit but prior to reaching the head space.

FIG. 8 illustrates a side view of a conduit 801 with respect to a container 817. Conduit 801 has an exit opening 803. Conduit 801 has a vertical portion and a non-vertical portion joined by a bend. The vertical portion defines and axis 809 and the non-vertical portion defines an axis 808. A plane 810 is defined by container opening 807. Axis 809 is vertical with respect to plane 810. Thus, angle D is substantially 90 degrees. It should be noted that this is an example only and the conduit 801 may be configured in any suitable manner.

In the illustrated example, the non-vertical portion has a vertical angular offset may be defined by either angle C or angle F. Preferably, the offset defined by angle F is in the range of from 15 to 40 degrees. More preferably, the range is from 25 to 35 degrees. Thus, defined by angle C, the offset is preferably from 140 to 165 degrees and more preferably from 145 to 155 degrees.

FIG. 9 illustrates an example embodiment in which the vertical offsets of two conduits 901 and 902 are different from one another. Inert gas exits first conduit 901 through exit opening 903 and in a first flow direction 908. Inert gas also exits second conduit 902 through exit opening 904 and in a second flow direction 909. The first and second flow directions 908 and 909 define a flow offset of E degrees. The first flow direction 908 is more toward the cap 915 (exiting from cap chute 913) than the second flow direction 909. Also, it may be stated that the first flow direction 908 is more toward the cap 915 than toward the container opening 907 of container 917. The second flow direction is also illustrated as being more toward the cap 915 than toward the container opening 907. However, either or both of the first and second flow directions may be more toward the container opening 907 than toward cap 917 (and still be offset from one another by E degrees).

FIG. 10 illustrates a process flow of a plurality of container 57 having openings 58. The container may be moved along a transport apparatus 60 toward a cap chute 53. As the container approach cap chute 53, it can be seen that a lateral axis of conduit 51 may be aligned with the direction of movement of the respective containers. Thus, a single conduit may supply inert gas through exit opening 52 directly toward the cap/container opening as the cap is being applied to the container. In certain other illustrations wherein two conduits are shown (and are angularly offset from the direction of movement of the container), the respective inert gas flow directions may cooperate with one another to produce a combined flow in the direction of movement of the container.

The invention has been shown in several embodiments. It should be apparent to those skilled in the art that the invention is not limited to these embodiments, but is capable of being varied and modified without departing from the scope of the invention. 

1. A method for extending shelf life of a potable liquid in a container sealed by a cap enclosing an opening of the container, the container and cap cooperating to define a head space above the potable liquid, comprising the step of: changing the relationship between the cap and opening from a first position to a second position, wherein a distance between the cap and opening is smaller at the first position than at the second position; introducing an inert gas toward the opening when the cap and opening are at the second position; and sealing the cap on the container with the inert gas enclosed in the head space, wherein the inert gas is delivered from an apparatus having an opening remote from a space defined by a projection of the opening of the container.
 2. The method of claim 1, wherein the cap is in contact with the container when the inert gas is introduced.
 3. The method of claim 1, wherein the apparatus comprises at least one conduit.
 4. The method of claim 1, wherein the apparatus comprises only one conduit.
 5. The method of claim 1, wherein the apparatus comprises a plurality of conduits.
 6. The method of claim 1, wherein the apparatus comprises at least one conduit having an axis angularly offset from a direction of movement of the container at the time the inert gas is introduced.
 7. The method of claim 6, wherein the angular offset is in the range of from 30 to 50 degrees.
 8. The method of claim 6, wherein the angular offset is in the range of from 40 to 45 degrees.
 9. The method of claim 1, wherein a direction of flow of the inert gas from the apparatus is angularly offset from a direction of movement of the container at the time the inert gas is introduced.
 10. The method of claim 1, wherein the apparatus comprises at least one conduit having an axis angularly offset from a plane defined by the opening of the container.
 11. The method of claim 10, wherein the angular offset is in the range of from 15 to 40 degrees.
 12. The method of claim 10, wherein the angular offset is in the range of from 25 to 35 degrees.
 13. The method of claim 1, wherein the apparatus comprises at least one conduit having a bend formed therein, the bend connecting a first conduit portion with a second conduit portion.
 14. The method of claim 13, wherein the first conduit portion defines a first axis and the second conduit portion defines a second axis, the second axis being coaxial with a direction of flow of the inert gas exiting the conduit.
 15. The method of claim 14, wherein the first axis is substantially perpendicular to a plane defined by the opening of the container.
 16. The method of claim 14, wherein an angle between the first and second axes is in the range of from 140 to 165 degrees.
 17. The method of claim 14, wherein an angle between the first and second axes is in the range of from 145 to 155 degrees.
 18. The method of claim 1, further comprising determining an exit area from which the inert gas exits the apparatus based at least in part on the size of the opening of the container.
 19. The method of claim 1, further comprising introducing the inert gas at a flow pressure and velocity determined not to displace the potable liquid from the container.
 20. The method of claim 19, wherein the flow pressure is in the range of from 10 to 30 psi.
 21. The method of claim 19, wherein the flow pressure is in the range of from 12 to 18 psi.
 22. The method of claim 19, wherein the flow pressure is about 15 psi.
 23. The method of claim 19, wherein the velocity is in the range of from 6-9 cfm.
 24. The method of claim 19, wherein the velocity is about 8 cfm.
 25. The method of claim 1, wherein the apparatus comprises at least a first conduit and a second conduit, a direction of flow of inert gas from the first conduit defining a first angle with respect to a plane defined by the opening of the container, and a direction of flow of inert gas from the second conduit defining a second angle with respect to the plane.
 26. The method of claim 25, wherein the first and second angles are substantially equal.
 27. The method of claim 25, wherein the first and second angles are offset.
 28. The method of claim 27, wherein the first angle is determined to direct the flow of inert gas from the first conduit more toward the cap than toward the opening of the container.
 29. The method of claim 28, wherein the second angle is determined to direct the flow of inert gas from the second conduit more toward the opening of the container than the flow of inert gas from the first conduit.
 30. The method of claim 27, wherein the second angle is determined to direct the flow of inert gas from the second conduit more toward the opening of the container than toward the cap.
 31. The method of claim 1, further comprising processing a plurality of containers, each of the containers having an opening, and wherein an inert gas exit opening of the apparatus is remote from spaces defined by projections of each of the container openings during the processing step.
 32. An apparatus for introducing an inert gas into a head space of a container, the container and cap cooperating to define the head space above a potable liquid in the container, the apparatus comprising: an inert gas source; a least one conduit coupled to the inert gas source, the at least one conduit having an exit opening for the inert gas to exit the at least one conduit; and a capping device for disposing a cap onto the container to seal the container, the apparatus operable to introduce an inert gas into the head space as the relationship between the cap and opening are changed from a first position to a second position, a distance between the cap and opening being smaller at the first position than at the second position, and wherein the exit opening of the at least one conduit is remote from a space defined by a projection of the opening of the container.
 33. The apparatus of claim 32, wherein the at least one conduit comprises only one conduit.
 34. The apparatus of claim 32, wherein the apparatus comprises a plurality of conduits.
 35. The apparatus of claim 32, wherein the at least one conduit has an axis angularly offset from a direction of movement of the container at the time the inert gas is introduced.
 36. The apparatus of claim 32, wherein a direction of flow of the inert gas from the at least one conduit is angularly offset from a direction of movement of the container at the time the inert gas is introduced.
 37. The apparatus of claim 32, wherein the at least one conduit has an axis angularly offset from a plane defined by the opening of the container.
 38. The apparatus of claim 32, wherein an exit opening of the at least one conduit has an area based at least in part on the size of the opening of the container.
 39. The apparatus of claim 32, wherein the at least one conduit comprises a first conduit and a second conduit, a direction of flow of inert gas from the first conduit defining a first angle with respect to a plane defined by the opening of the container, and a direction of flow of inert gas from the second conduit defining a second angle with respect to the plane.
 40. The apparatus of claim 39, wherein the first and second angles are substantially equal.
 41. The apparatus of claim 39, wherein the first and second angles are offset.
 42. The apparatus of claim 39, wherein the first angle is determined to direct the flow of inert gas from the first conduit more toward the cap than toward the opening of the container.
 43. The apparatus of claim 39, wherein the second angle is determined to direct the flow of inert gas from the second conduit more toward the opening of the container than the flow of inert gas from the first conduit.
 44. The apparatus of claim 39, wherein the second angle is determined to direct the flow of inert gas from the second conduit more toward the opening of the container than toward the cap. 